Interacting theory of the oscillatory response

Develop an interacting theory of the oscillatory de Haas–van Alphen response of flat-band systems, extending beyond the noninteracting treatment and the existing mean-field approaches for the smooth orbital response.

Background

The paper derives the smooth orbital susceptibility and the oscillatory de Haas–van Alphen response of an isolated, nondegenerate flat band using the field-generated dispersion, Berry-curvature phase-space measure, and bosonization of the emergent Fermi contour. These results are explicitly noninteracting.

The authors note that flat bands amplify interaction effects. Although interacting mean-field frameworks provide a concrete route for treating the smooth response through field-dependent Hartree–Fock bands, a corresponding theory for the oscillatory response has not yet been established. Developing such a theory would extend the geometric Lifshitz–Kosevich framework to interacting flat-band systems.